From dc0dc8a73e8e4dc33fba93dfe23356cc5a500c57 Mon Sep 17 00:00:00 2001

From: Takashi Iwai <tiwai@suse.de>

Date: Sun, 8 Aug 2021 09:01:16 +0200

Subject: [PATCH] ALSA: pcm: Fix mmap breakage without explicit buffer setup

Git-commit: dc0dc8a73e8e4dc33fba93dfe23356cc5a500c57

Patch-mainline: v5.14-rc6

References: git-fixes

The recent fix c4824ae7db41 ("ALSA: pcm: Fix mmap capability check")

restricts the mmap capability only to the drivers that properly set up

the buffers, but it caused a regression for a few drivers that manage

the buffer on its own way.

For those with UNKNOWN buffer type (i.e. the uninitialized / unused

substream->dma_buffer), just assume that the driver handles the mmap

properly and blindly trust the hardware info bit.

Fixes: c4824ae7db41 ("ALSA: pcm: Fix mmap capability check")

Reported-and-tested-by: Jeff Woods <jwoods@fnordco.com>

Cc: <stable@vger.kernel.org>

Link: https://lore.kernel.org/r/s5him0gpghv.wl-tiwai@suse.de

Signed-off-by: Takashi Iwai <tiwai@suse.de>

---

 sound/core/pcm_native.c | 5 ++++-

 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c

index 09c0e2a6489c..71323d807dbf 100644

--- a/sound/core/pcm_native.c

+++ b/sound/core/pcm_native.c

@@ -251,7 +251,10 @@ static bool hw_support_mmap(struct snd_pcm_substream *substream)

 	switch (substream->dma_buffer.dev.type) {

 	case SNDRV_DMA_TYPE_UNKNOWN:

-		return false;

+		/* we can't know the device, so just assume that the driver does

+		 * everything right

+		 */

+		return true;

 	case SNDRV_DMA_TYPE_CONTINUOUS:

 	case SNDRV_DMA_TYPE_VMALLOC:

 		return true;

-- 

2.26.2